This invention relates to an exhaust gas driven supercharger for supercharging internal combustion engines. The supercharger has a supercharging chamber, that is subdivided by a moving partition into an exhaust gas chamber having an exhaust gas inlet and an exhaust gas outlet, and a supercharging air chamber with a supercharging air inlet and a supercharging air outlet.
Positive displacement superchargers driven by exhaust gas are known as a theoretical possibility. However, the utilization of the exhaust gas energy periodically leaving one of the cylinders of the internal combustion engine has shortcomings in many cases. For example, it is frequently the case that the exhaust gas pulse from the internal combustion engine available at the supercharger is too short in duration to outbalance the inertia of the partition such as a piston in order to produce an efficient supercharging stroke.
In the case of four cylinder engines, the exhaust gas pulses mutually hinder each other since there is little time duration between pulses so that, with an increase in the number of cylinders, there is less and less available energy gradient for driving the partition of a positive displacement supercharger by means of the natural exhaust gas pulses. A similar effect occurs at high engine speeds.
The object of this invention is to optimize the exhaust gas pulses used for driving a positive displacement supercharger in a way which is independent of the number of cylinders of the engine and its operating speed. In accordance with the invention, its operating means are placed in the exhaust path of an internal combustion engine for modifying the pulse duration and/or the pulse frequency supplied to an exhaust gas driven supercharger.
In keeping with a useful form of the invention, the exhaust gas outlet of the internal combustion engine is fitted with a choke means which, as part of a further useful form of the invention, may be controlled with respect to pressure and/or duration of the choking action.
In another possible form of the invention, the exhaust gas inlet or the exhaust gas outlet of the supercharger may be fitted with a valve controlled by a pulse generator.
A particularly useful form of the invention is one in which the exhaust gas inlet of the exhaust gas chamber is placed downstream from an exhaust gas collector and the exhaust gas side of the supercharger is fitted with a pulse generator, the exhaust gas side of the supercharger being preferably fitted with an inlet and/or an outlet valve.
Preferably the controller for the exhaust gas side of the supercharger may be fitted with an electronic automatic controller processing the operating data of the engine and/or of the supercharger and/or of the vehicle.
If it is desired to make these above measures even more effective, for example in the case of engines with a very large number of cylinders, then as part of a further useful teaching of the invention, the supercharger may have a further exhaust gas chamber having an additional moving partition, the two partitions being ganged together for joint motion and being able to be acted upon by exhaust gas in the two exhaust gas chambers in opposite directions. The outcome is that the number of the engine cylinders acting on one exhaust gas chamber may be reduced to half as many. In conjunction with the measures for increasing the pulse duration or for changing the pulse frequency, it is then possible to cope even when unfavorable working conditions for exhaust-powered positive displacement superchargers. A similar method effect is produced if a number of exhaust gas superchargers are used that each has one exhaust gas chamber and a supercharging air chamber.